Aaron begins his high-stakes masquerade by infiltrating the castle's annual hiring fair, desperate to secure a position that will keep him warm through the harsh winter. However, his plans are instantly derailed when the warning bells toll for the discovery of Markus's murdered body, prompting the suspicious royal guard to hunt down the look-alike street rat. Dragged into the dark interrogation rooms, Aaron is confronted by the sharp-eyed Second Lieutenant Lochlann Varghese, who utilizes a piece of magical kirin's bone to force absolute honesty from his prisoner. Trapped by a truth-inducing relic, Aaron brilliantly navigates the questioning by speaking literal truths, admitting he is not a doppelganger and had no hand in the murder, though his survival remains precarious. His luck shifts when a mysterious, fey-marked girl he encountered in the cells leaves him a sturdy bronze hair pin shaped like a leaping fox, allowing him to pick his locks and slip past the slumbering guards. He navigates the pitch-black servants' passages to the kitchens, where the naive enclave apprentice John Baker turns a blind eye to his escape, but Aaron's bid for freedom is cut short as he hits the courtyard. The sky bleeds blue as the legendary four-tailed fox launches a terrifying assault on the castle gates, summoning a forest of cobalt flames and illusory beasts that throw the garrison into absolute chaos. Forced to defend his life, Aaron uses a tiny carving knife to slay a very real wolf, earning a begrudging temporary alliance with Lochlann as the crown prince Orin O'Shea and the gnarled Iron Captain face down the monstrous intruder. The climax escalates when the king himself steps out to negotiate with the vengeful beast, only for the legendary Lady of the Late Wake to arrive on a massive griffin, tearing off her beastly skin to reveal her human form and forcing the fox to retreat. Just as the chaos subsides, Lochlann recaptures Aaron and drags him before the Lady, who instantly recognizes the charcoal sketch of the dead Markus and demands to see the mysterious boy who holds the key to the kingdom's deepest secrets.

Following the siege, the Lady of the Late Wake conducts a private interview with Aaron, mistaking him for her high-born son Markus who she believes is playing the part of a street rat to act as a deep-cover spy. Aaron plays along with the script fed to him by Markus's dramatic Death, dropping a shocking warning about an impending assassination attempt on the crown prince to solidify his value to the court. Reassigned as a humble errand runner under the scowling housekeeper Mrs. Summers, Aaron begins to heal, using his free time to practice knife fighting and secret lessons with the fey-marked Princess Rose. The princess, who is actually the mysterious library girl with the wine-stain birthmark, easily sees through his noble facade, revealing she knows he is an imposter because he cannot read the ludicrous volumes she leaves in his room. Instead of exposing him, the lonely princess offers him her fierce loyalty, initiating him into the secrets of the castle's ancient, blood-activated hidden passages that only those of royal blood can open. Their secret alliance deepens as Rose teaches him his letters, and they spend their nights on the high castle roofs, overlooking the vast, dark kingdom while trading confidences about their fractured families. However, the fragile peace is shattered when the deadly Kindly Souls assassins strike the royal apartments, forcing Aaron to act on pure instinct as he runs to defend the princess from a knife to the throat. In a frantic, brutal struggle, Aaron slides his dagger between the ribs of Gwendolyn, a deadly assassin who was once his friend in the Downs, saving Rose's life but leaving himself gravely wounded by a poisoned blade. As he collapses into a deep, feverish slumber, the royal family gathers around his bed, fully convinced by the Lady's cover story that the heroic Lord Markus Yin Sung has risked everything to protect the crown.

Aaron wakes from his month-long fever to find himself treated as a noble hero, but his recovery is cut short by the dramatic arrival of Duke Sung and the powerful southern lords. The duke presents a terrifying petition before the royal council, demanding the disinheritance and execution of Crown Prince Orin, claiming the prince was doppeled by a dragon during his capture at Salt's Mane. To back his claim, the duke systematically lists the suspicious, tragic deaths of Orin's entire military unit, weaving a compelling narrative of a dragon doppelganger executing his own men to hide his monstrous identity. The tension reaches a boiling point when the failing King Liam reveals that the four-tailed fox has been murdered and its tongue cut out, meaning any man who ate it could stand on the kirin's bone floor and speak absolute lies without detection. As the council dismisses the petition for further investigation, Aaron meets with the Lady in her private rooms, only to uncover a horrifying truth that shatters his understanding of the conspiracy. The Lady casually reveals that she was the one who ordered the street rat named Aaron to be knifed in the back to clean up the noble succession line, entirely unaware she had murdered her own beloved son Markus instead. Furthermore, she admits to poisoning the late king with her nightly medicines, framing her own husband to ensure her children inherit the throne under her ruthless guidance. Realizing he is trapped in a deadly game with a mother who murdered her own son, Aaron decides to play the role of Markus to its absolute limit, plotting a silent, poetic vengeance against the woman who stole his original life.

The sudden death of King Liam triggers the ascension of Orin O'Shea, forcing the royal court and the southern forces to march to the coastal fortress of Salt's Mane to face the spring dragon hatching. Aaron travels with the army as a royal messenger, but his cover is immediately threatened when he is confronted by his sharp-eyed half-sister, Adelaide Sung, who notices his shortened height and demands his true identity at knifepoint. Their tense standoff is violently interrupted as a terrifying storm rolls in, bringing with it a coordinated assault of adolescent dragons scaling the sheer cliffs of the fortress. Bracing against the howling wind and rain, Aaron leaps onto a thrashing dragon's back, distracting the beast so Adelaide can deliver a lethal blow, saving her life but exposing his lack of noble training. As the battle rages, Aaron realizes the dragons are displaying unprecedented, coordinated tactics, specifically targeting high-ranking blood nobles while leaving the suspected doppelganger king Orin entirely untouched. Seizing the opportunity, Aaron confronts the stressed young king, offering to expose the Lady's treasonous plot to murder the late ruler in exchange for a full royal pardon signed by both Orin and Prince Connor. The king agrees, appointing Aaron as his official messenger to the southern investigation committee, setting the stage for a grand political counter-play that will decide the fate of the realm. But as the dragons retreat and the fortress prepares for a prolonged siege, Aaron must return to the capital to face the Lady, knowing his final test of flight and survival has only just begun.